Process and product to inhibit sugar inversion



United States atent O PROCESS AND PRODUCT T INHIBIT SUGAR INVERSION Joe W. McGahen, Wilmington, Del., assignor to E. I. du Pont de Nemours and Company, Wilmington, Del., a corporation of Delaware No Drawing. Application June '19, 1957 Serial No. 666,756

. Claims.' (Cl. 1 27-30) This invention is directed to preventing sucrose inversion in sugar cane juice and is more particularly directed to compositions and methods for controlling microorganisms causing sucrose. inversion in' raw sugar cane juice.

In the manufacture of sugar from sugar cane, the juice of the sugar cane stalk is first extracted from shredded cane by crushing the cane between rollers. The shredded cane passes through a series of rollers with water or thin juice being added to the cane macerate to further facilitate extraction. The juice obtained is acid, having a pH usually between about 5.0 and 5.5, and its temperature is below 55 C. The sucrose in this juice is subject to undesirable inversion due to the metabolic activities of microorganisms present.

Inversion proceeds in this juice until the clarification step when the juice is heated to a temperature above 200 F. and also is made alkaline by raising the pH to about 7.5 to 8.3 through lime addition. No microbial inversion difliculties are encountered in the cane juice after clarification in subsequent manufacturing states.

This sucrose inversion in raw cane juice by microorganisms during extraction and prior to clarification results in a build-up of invert sugars. Such inversion not only causes a loss of product but also makes the crystallization of sucrose difiicult and expensive. The microorganism chiefly responsible for such inversion is Leuconostoc mesenteroides (Cienkowski) Van Tieghem.

It has now been found that the inversion losses can be avoided by treating the raw cane juice with one or more compounds selected from the following general formula:

where R and R are the same or difierent alkyl groups of 1 through 4 carbon atoms.

These compounds and methods for their preparations are disclosed in U.S. patent application Serial No.

657,721, filed May 8, 1957.

The compounds within the scope of Formula 1 above are particularly suitable for preventing microbial inversion of sucrose in sugar manufacture. These compounds have been found to exhibit a high degree of activity against the microorganisms commonly found in raw cane juice which cause sucrose inversion. The compounds are not highly toxic to warm-blooded animals and they are not corrosive to such equipment as is usually found in a sugar mill.

Also, the compounds have the unusual property of being stable at low pH and low temperatures while being unstable at high pH and somewhat elevated temperatures. Thus, the compounds are destroyed during the clarification step of the sugar manufacturing process and their decomposition products do not crystallize under the conditions employed to crystallize sucrose.

Thus, in practice, one or more compounds selected from Formula 1 are added to raw cane juice. The active compound or compounds used are applied at amounts suflicient to exert the desired prevention or control of 2,900,283 Patented Aug. 18, I959 "ice control under usual conditions during the entire length of time after extraction and prior to clarification.

In order that the invention can be better understood, the following specific illustrative examples are given in addition to those already indicated above.

EXAMPLE 1 A series of determinations were carried out with organisms isolated from raw can juice wherein the amounts of 3,3-bis(ethylsulfonyl)propionitrile necessary to give complete or partial inhibition of growth were'described. In these determinations, seven organisms which had been isolated from raw cane juice by appropriate bacteriological methods and grown in pure culture were used. To a growth medium containing 1% Bacto peptone,"0.'5% yeast extract and 10% sucrose and to canejuice which had been heated and filtered in order to remove solid material, amounts of 3,3-bis(ethylsu1fonyl)propionitrile were added to obtain concentrations of 40, 20, 8, 6, 4, 2', and'l micrograms per milliliter. The growth medium and the cane juice containing the inhibitor were inoculated with pure cultures of the seven organisms and. incubated at 37 C. for 19 hours after which time growth was determined. Table 1 sets forth these determinations:

Table 1 Meg. per ml. 11 for Inhibition Organism 10.

Medium Inhibition Partial Growth MedumL- {gontifletmn 20 2(1) 20 20 20 20 10 ar a 1 Cane Juice lComplete-.- 2 2 1 2 EXAMPLE 2 Percent of Inhlbltlon of Meg/ml. of 3, 3-bls(ethylsulionyl)proplonitrfle I Fermentatlozr EXAMPLE 3 Subsequent to sucrose inversion, an increase of acidity due to the production of acid by microorganisms occurs in raw cane juice. The acidity is undesirable since manufacturing difficulties are encountered-particularly filtration difficulties. In order to describe the effect of 3,3 bis(ethylsulfonyl)propionitrile on microbial acid production, a series of determinations were carried out wherein- EXAMPLES 6-12 In extracting the juice from sugar cane, the cane is chopped and shredded without loss of juice and then crushed between rollers. The shredded cane passes w of Leuconostoc' mesememides' The PH changes throu h a series of rollers with water or thin juice being were determined after various incubation periods. These addecf to the macerate after each roller except the last detenmnanons are set forth mTable 3: one. The cane juice is pumped to weighing tanks. The

Table 3 pH of the fresh juice is acid (5.0-5.5). From the weighing tanks the juice is pumped to liming tanks where the Units pH change aft r temperature is raised to above 200 F. and the pH is Moe/m1 M g Hours Incubation raised to 7.5-8.3. In the method described in the present prop o r e invention, one or more of the compounds of Formula 1 7 24 28 31 48 are added to the cane juice prior to its being pumped to the weighing tanks. The cane juice is protected against 8 3- 2 sucrose inversion caused by microorganisms before being L9 1 heated and limed. The compounds are then destroyed by the high temperature and the high pH of the juice in the liming tanks and subsequent processing steps. The EXAMPLE 4 2 amounts of the compounds of Formula 1 necessary to A series of determinations were carried out to describe 0 Provide dfisiled P of raw cane llliw from the eifects of 3,3-bis(ethylsulfonyDpropionitrile on susucrose mvertlon are set forth m Table 6: crose inversion. To a growth medium containing 1% Bacto peptone, 0.5% yeast extract and 10% sucrose, amounts of 3,3-bis(ethylsulfonyl)propionitrile were added Table 6 toequal 10 and 20 micrograms per milliliter. The growth medium containing the compound was inoculated with a Effective pure culture of Leuconostoc mesenleroides and the inhif g g gg 25525 bition of sucrose inversion determined at various incuba- Example Compound to Raw before Eflects tion, periods. The inhibition of sucrose inversion is set af gg forth in Table 4: Toni Heating,

Table 4 0 3,3-bis(methylsul- 0.06-0.08 s lnhibiuonor Meg/ml. of 3.3-bis(et hylsigii g iiiiiiis i uiia ti ii 25; Upmpmi' $83315? sulfonynpropionitrile acid produc- 7 33-bis(ethylsul- 0 02-0 04 8-24 ia ig 13( 1% i2 2359m 40 R 3,3-hls(propylsu 1 0.06-0.08 8 D0. EXAMPLE 5 iiiiip 9 3,3-bls(butylsul- I 0.08-0.12 8 Do.. A series of stability determinations were carried out by fo yvp p adjusting solutions of 3,3-bis(ethylsulfonyl)propionitri1e 10 m3 m 8 Do to pHs of 2.7, 6.6, and, 7.6 with phosphate buffer and aethylsul p r heating in a water bath atv 100 C. for various periods. gfigflfifiii; 0.04.0418 The stability was determined by assaying the solutions a-p opyl u o y by a method wherein an amount of the solution was It ggtgggfl'gg 8 placed on a filter paper disk, the disk placed on the surutyls t y face of nutrient agar medium seeded with Candida albipmpmmmle' cans and after inclubation determining the zone of inhibition around the disk. The results of the foregoing determinations are set forth in Table. 5,: I claim.

Table 5 1. The method of inhibiting sucrose inversion caused by microorganisms in raw cane juice comprising the addi- Time (Mm) pH Zone size Percent of tion to such juice of at least one compound selected from ture, 0. (mm.) 0 Time the formula;

0. a a... ge 13( o 100 ()IHI-(JIEIzCN 5 s. g 100 $13 3: R140 7.1 100 24.3 82 0.0 25 32.5 102 a %g 2%? 3; where R and R are each selected from the group 6011: 100 79 5 sisung of alkyl groups containing 1 through 4 carbon 6. 7 25 32. 0 102 atoms. 2.7 100 33.2 99 m 6, 100 29,2 5 2. composition adapted for the prevention of sucrose g-g gg 5 g}, inversion which contains raw cane sugar uice admixed 100 1 97 with at least about 0.02 pound per ton of at least one 40 g-g igg -3 g compound represented by the formula described in 010 25 31.2 98 claim g-g h 8 g? 3. The method of mhibitmg sucrose inversion caused 105 100 0 by microorganisms in raw cane juice comprising the 25 addition to such juice of at least about 0.02 pound-"per ton of 3,3.-bis-(ethylsulfonyDpropionitrile.

4. The method of inhibiting sucrose inversion caused by microorganisms in raw cane juice comprising the addition to such juice of about 0.02 1b. to 0.1 'lb. per ton of 3,3-bis(ethylsulfonyl)propionitrile.

5. A composition adapted for the prevention of sucrose inversion which contains raw sugar cane juice admixed with at least about 0.02 pound per ton of 3,3-bis(ethy1- su1fony1)propionitrile.

6 References Citedin the file of this patent UNITED STATES PATENTS Heininger Aug. 6, 1957 OTHER REFERENCES Bohme et aL: Chem. Abstr., vol. 40 (1944), pp. 2809- 2811. 

1. THE METHOD OF INHIBITING SUCROSE INVERSION CAUSED BY MICROORGANISMS IN RAW CANE JUICE COMPRISING THE ADDITION TO SUCH JUICE OF AT LEAST ONE COMPOUND SELECTED FROM THE FORMULA: 